Heating Device

ABSTRACT

A heating device includes a housing, a primary induction coil, a controller circuit, and a secondary induction coil. The housing is configured to retain a camera lens. The primary induction coil is positioned proximate the housing and configured to generate a magnetic field in response to receiving electrical power from a power supply. The controller circuit is in electrical contact with the primary induction coil and is configured to control the electrical power delivered to the primary induction coil. The secondary induction coil overlays the primary induction coil and is configured to receive the magnetic field from the primary induction coil and generate heat. The secondary induction coil heats the camera lens when the primary induction coil receives the electrical power.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Pat. Application No.16/713,104, filed Dec. 13, 2019, which claims priority to EuropeanPatent Application No. 18213511.1, filed Dec. 18, 2018, the disclosuresof which are hereby incorporated by reference in their entiretiesherein.

TECHNICAL FIELD

The present disclosure relates generally to a heating device that clearscondensation from a camera lens.

BACKGROUND

Typical heating devices require electrical terminals and wiring attachedto a windshield or cover-glass. U.S. Pat. Application Publication No.2006/0171704 A1 describes a heating element for heating a transparentcamera lens cover that includes electrical terminals in contact with asurface of the transparent camera lens cover. Other applicationsdescribe a heating element positioned on a lens holder and resilientcontacts used to heat a camera lens.

SUMMARY OF THE DISCLOSURE

The present disclosure proposes to solve the above mentioned problem byproviding a heating device comprising a housing configured to retain acamera lens, a primary induction coil positioned proximate the housingand configured to generate a magnetic field in response to receivingelectrical power from a power supply, a controller circuit in electricalcontact with the primary induction coil configured to control theelectrical power delivered to the primary induction coil, and asecondary induction coil overlaying the primary induction coil, thesecondary induction coil configured to receive the magnetic field fromthe primary induction coil and generate heat. The secondary inductioncoil heats the camera lens when the primary induction coil receives theelectrical power.

According to other features of the present disclosure:

-   the primary induction coil surrounds an optical axis of the camera    lens;-   the secondary induction coil is interposed between the primary    induction coil and the housing;-   the secondary induction coil is in direct contact with the housing;-   the secondary induction coil is located on an outer surface of the    housing;-   the secondary induction coil is located on an inner surface of the    housing;-   the secondary induction coil is in direct contact with the camera    lens;-   the controller circuit includes a low-Q resonant circuit in    electrical communication with the primary induction coil;-   the secondary induction coil is comprised of a first layer of    resistive material and a second layer of low-Curie point ferrite;-   the secondary induction coil is formed of a conductive material    having a greater electrical resistance relative to the primary    induction coil;-   adjoining segments are formed of materials having a different    electrical conductivity from one another;-   a distance between the primary induction coil and the secondary    induction coil is in a range from 0.0 mm to 10.0 mm;-   a number of windings on the primary induction coil is at least one;-   a number of windings on the secondary induction coil is at least    one;-   the secondary induction coil has a thickness in a range from 1 µm to    1000 µm;-   the secondary induction coil has a width in a range from 0.1 mm to 5    cm.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure is now described by way of example with referenceto the accompanying drawings in which:

FIG. 1 is an exploded perspective view of a heating device according toan embodiment of the disclosure;

FIG. 2 is a section view of the heating device of FIG. 1 ;

FIG. 3 is a section view of a portion of the heating device of FIG. 2 ;

FIG. 4 is a schematic of the heating device of FIG. 1 illustrating acontroller circuit;

FIG. 5 is a section view of the heating device of FIG. 1 in accordancewith another embodiment.

DESCRIPTION OF THE EMBODIMENTS

Hereinafter, a heating device 10 for a camera lens 14 according to anembodiment of the present disclosure will be described with reference tothe figures. FIG. 1 is an exploded perspective view illustrating theheating device 10, hereafter referred to as the device 10. The device 10includes a housing 12 configured to retain the camera lens 14. Thehousing 12 may be formed of any material, such as a polymeric material,a ceramic, or a metal. Preferably, the housing 12 is formed of adielectric material, such as the polymeric material, or the ceramicmaterial. That is, the housing 12 preferably would not have electricallyconductive properties, which has the technical benefit of lower thermalresistance and lower electrical losses. The housing 12 may have acircular cross section or may have any other cross section, such as arectilinear cross section. The housing 12 may include an imager 15 usedto render an image of a surrounding area. The camera lens 14 defines afield-of-view 16 and an optical axis 18 as illustrated in FIG. 1 . Thehousing 12 may be mounted on a front of a vehicle, on sides of avehicle, on a rear of a vehicle, or mounted in the interior of thevehicle at a location suitable for the camera to view the area aroundthe vehicle through the windshield 20. In the examples illustratedherein, the housing 12 is mounted inside the vehicle with the viewthrough the windshield 20.

The device 10 also includes a primary induction coil 22 positionedproximate the housing 12 and is configured to generate a magnetic field24 in response to receiving electrical power 26 from a power supply 28.The power supply 28 may be a direct-current (DC) power supply 28, or maybe an alternating-current (AC) power supply 28. In the examplesillustrated herein the power supply 28 is an AC power supply 28. Theprimary induction coil 22 surrounds the optical axis 18 of the cameralens 14 and may also surround a portion of the housing 12. A number ofwindings 30 (e.g., wires, conductive traces, etc.) on the primaryinduction coil 22 is at least one, and are preferably wound onto aferromagnetic core 32 (e.g. iron, ferrites, etc.). In the exampleillustrated in FIG. 1 , the ferromagnetic core 32 encircles the primaryinduction coil 22. It will be appreciated that the number of windings 30will increase with the increasing size of the area required to beheated. It will also be appreciated that the ferromagnetic core 32 maybe omitted (i.e., an air core coil) depending on packaging and weightconstraints. A single winding 30 (i.e. a single wire) of the primaryinduction coil 22 may be any diameter, and in the examples illustratedherein, preferably has the diameter in a range from 0.2 mm to 1.0 mm.The windings 30 may be formed of any electrically conductive material,such as copper alloys or aluminum alloys, and may include a dielectriclayer on a surface of the windings 30.

The device 10 also includes a controller circuit 34 in electricalcontact with the primary induction coil 22. The power supply 28 may beseparate or integral to the controller circuit 34, and in the examplesillustrated herein, the power supply 28 is integral to the controllercircuit 34. The controller circuit 34 is configured to control theelectrical power 26 delivered to the primary induction coil 22. Thecontroller circuit 34 may include a processor (not shown) such as amicroprocessor or other control circuitry such as analog and/or digitalcontrol circuitry including an application specific integrated circuit(ASIC) for processing data as should be evident to those in the art. Thecontroller circuit 34 may include a memory (not shown), includingnon-volatile memory, such as electrically erasable programmableread-only memory (EEPROM) for storing one or more routines, thresholds,and captured data. The one or more routines may be executed by theprocessor to perform steps for determining the electrical power 26delivered to the primary induction coil 22 based on signals received bythe controller circuit 34 from the primary induction coil 22, asdescribed herein.

The device 10 also includes a secondary induction coil 36 overlaying theprimary induction coil 22. That is, the secondary induction coil 36 isencircled by the primary induction coil 22. The secondary induction coil36 is configured to receive the magnetic field 24 from the primaryinduction coil 22, thereby generating heat 38. The magnetic field 24from the primary induction coil 22 induces an electrical current in thesecondary induction coil 36. The induced electrical current in thesecondary induction coil 36 causes the secondary induction coil 36 toincrease in temperature because the secondary induction coil 36 isformed of a material that has an electrical resistance. The electricalresistance of the secondary induction coil 36 resists the flow ofelectrical current within the secondary induction coil 36, whichgenerates the heat 38 (also known as Joule heating or Ohmic heating). Itwill be appreciated that no wire connections exist between the primaryinduction coil 22 and the secondary induction coil 36. This has thetechnical benefit of reducing a size and complexity of the overallassembly.

The secondary induction coil 36 also surrounds the optical axis 18 and,in the example illustrated in FIG. 1 , is both interposed between theprimary induction coil 22 and the housing 12, and is in direct contactwith an outer surface 43 of the housing 12. In an embodiment, thesecondary induction coil 36 is located on an inner surface 42 of thehousing 12 and is in direct contact with an outer-diameter of the cameralens 14 (see FIG. 5 ).

The secondary induction coil 36 heats the camera lens 14 and the housing12, and removes condensation (e.g., fog, ice, etc.) when the primaryinduction coil 22 receives the electrical power 26 from the controllercircuit 34. A heating rate and a maximum temperature is controlled toinhibit a thermal shock to the housing 12 and/or camera lens 14, andalso to prevent an unsafe surface temperature for human contact.

FIG. 2 is a section view of the device 10 and illustrates the embodimentwhere the secondary induction coil 36 is located on the outer surface 43of the housing 12. A distance 46 between the primary induction coil 22and the secondary induction coil 36 is preferably in a range from 0.0 mmto about 10.0 mm. The distance 46 primarily impacts a coupling of theprimary induction coil 22 and the secondary induction coil 36. Thesecondary induction coil 36 has a width 49 preferably in a range fromabout 0.1 mm to about 5 cm. It will be appreciated that the width 49 ofthe secondary induction coil 36 affects the heat transfer to the housing12 and camera lens 14. The width 49 may be user defined depending on adesired heating profile for the housing 12 and/or camera lens 14.

The number of windings 30 on the secondary induction coil 36 is at leastone, and may be increased to achieve a specific temperature profileapplied to the housing 12. The windings 30 on the secondary inductioncoil 36 may be a single flat winding 30 that may be deposited using athick-film ink, for example. The secondary induction coil 36 asillustrated in FIG. 2 has a thickness 48 in the range from about 1 µm toabout 1000 µm. The thickness 48 may be adjusted based on the type ofmaterial comprising the secondary induction coil 36, and based on afrequency 50 of the electrical power 26 delivered to the primaryinduction coil 22. In an embodiment, the secondary induction coil 36 hasa thickness 48 of 400 µm and is formed of a material with a low relativemagnetic permeability (e.g., silver, aluminum, etc.). In anotherembodiment, the secondary induction coil 36 is formed of a materialhaving higher magnetic permeability (e.g., iron) having a thickness 48of 15um. The thickness 48 may also be reduced by increasing thefrequency 50 of the of the electrical power 26 delivered to the primaryinduction coil 22.

FIG. 3 is a magnified view of a portion of the device 10 of FIG. 2 . Thesecondary induction coil 36 is preferably comprised of a first layer 52of resistive material that dissipates the power transmitted by themagnetic field 24, and a second layer 54 of low-Curie point ferrite.When the secondary induction coil 36 reaches a Curie point temperature(e.g. approximately 90° C. for a Mn-Zn ferrite at 8 µm-9 µm thickness48), a magnetic permeability of the second layer 54 is decreased,thereby reducing the induced heating of the secondary induction coil 36.This reduction of the induced heating of the secondary induction coil 36changes a resonant frequency of a control circuit 56, the benefit ofwhich will be described in more detail below. Preferably, the secondaryinduction coil 36 is formed of a conductive material having a greaterelectrical resistance than that of the primary induction coil 22. Thefirst layer 52 and the second layer 54 may also have a protectivecoating (not specifically shown) applied to their exposed surfaces toimprove a durability of the layers.

Referring back to FIG. 1 , the secondary induction coil 36 may becharacterized as segmented 58, wherein adjoining segments 58 are formedof materials having a different electrical conductivity from oneanother. That is, a first-segment may have a relatively low electricalresistance thereby emitting a relatively low quantity of heat 38,wherein a second-segment in contact with the first-segment may have ahigher electrical resistance compared to the first-segment, therebyemitting a larger quantity of heat 38 than the first-segment. Thissegmentation 58 has the technical benefit of enabling a specific heatingprofile on the housing 12 and/or on the camera lens 14. For example,preferentially heating corners of a rectangular housing 12 where thecorners are a greater length away from the optical axis 18 compared to aside of the rectangular housing 12 that may be closer to the opticalaxis 18. It will be appreciated that other patterns of segmentation 58are possible based on a geometry of the housing 12 and/or a geometry ofthe camera lens 14.

FIG. 4 is a schematic diagram of the device 10 illustrating thecontroller circuit 34. The controller circuit 34 preferably includes alow-Q resonant control circuit 56 in electrical communication with theprimary induction coil 22. A Q-factor (i.e., quality factor) of anelectronic circuit is a parameter that describes the resonance behaviorof a harmonic oscillator or resonator. The low-Q factor is indicative ofan overdamped system that does not resonate or oscillate. The low-Qresonant control circuit 56 has the technical benefit of improvedtemperature control in the secondary induction coil 36. It will beappreciated that the values of capacitors C1 and C2 (not specificallyshown) may be selected to achieve the desired resonant frequency todrive the secondary induction coil 36 and produce the desired heat 38.The temperature of the secondary induction coil 36 may be controlled byadjusting a voltage 62 applied to, and/or adjusting the frequency 50 ofa signal delivered to, the primary induction coil 22 through the MOSFETsM1 and M2 (not specifically shown) and through the power supply 28. Thecontroller circuit 34 is configured to monitor an impedance of theprimary induction coil 22, which is directly related to the temperatureof the secondary induction coil 36, and controls the voltage 62 and/orfrequency 50 (e.g. 40 kHz) to maintain proper operation of the controlcircuit 56. This method of temperature measurement has the technicalbenefit of eliminating a separate temperature sensor mounted to thewindshield 20.

FIG. 5 is a section view of another embodiment where the secondaryinduction coil 36 surrounds the outer diameter of the camera lens 14.The secondary induction coil 36 is also in direct contact with thecamera lens 14 and has the technical benefit of conductive heat transferdirectly to the camera lens 14. In the example illustrated in FIG. 5 ,the secondary induction coil 36 is located on the inner surface 42 ofthe housing 12. It will be appreciated that the dielectric properties ofthe housing 12 enable the embodiment illustrated in FIG. 5 and will notinterfere with the coupling of the primary induction coil 22 and thesecondary induction coil 36. It will also be appreciated that thesecondary induction coil 36 of the embodiment of FIG. 5 is not limitedto locations internal to the housing 12. That is, the housing 12 may bepartitioned by the secondary induction coil 36, with a first section ofthe housing 12 terminating at a first-side of the secondary inductioncoil 36 and a second section of the housing 12 extending from a secondside of the secondary induction coil 36. In this arrangement, thesecondary induction coil 36 may be flush with the outer surface 43 ofthe housing 12.

What is claimed is:
 1. A heating device comprising: a housing configuredto retain a camera lens; a primary induction coil positioned proximatethe housing and configured generate a magnetic field in response toreceiving electrical power from a power supply; a controller circuit inelectrical contact with the primary induction coil and configured tocontrol the electrical power delivered to the primary induction coil;and a secondary induction coil configured to receive the magnetic fieldfrom the primary induction coil and generate heat to heat the cameralens, at least a portion of the secondary induction coil being encircledby the primary induction coil.
 2. The heating device of claim 1, whereinthe primary induction coil surrounds an optical axis of the camera lens.3. The heating device of claim 1, wherein the secondary induction coilis positioned between the primary induction coil and the housing.
 4. Theheating device of claim 3, wherein the secondary induction coil is indirect contact with the housing.
 5. The heating device of claim 3,wherein the secondary induction coil is located on an outer surface ofthe housing.
 6. The heating device of claim 1, wherein the secondaryinduction coil is in direct contact with the camera lens.
 7. The heatingdevice of claim 1, wherein the controller circuit includes a low-Qresonant circuit in electrical communication with the primary inductioncoil.
 8. The heating device of claim 1, wherein the secondary inductioncoil is comprised of a first layer of resistive material and a secondlayer of low-Curie point ferrite.
 9. The heating device of claim 1,wherein the secondary induction coil is formed of a conductive materialhaving a greater electrical resistance than a material of the primaryinduction coil.
 10. The heating device of claim 1, wherein the secondaryinduction coil is segmented and adjoining segments are formed ofmaterials having a different electrical conductivity from one another.11. The heating device of claim 1, wherein a distance between theprimary induction coil and the secondary induction coil is in a rangefrom 0.0 mm to 10.0 mm.
 12. The heating device of claim 1, wherein anumber of windings on the primary induction coil is at least one. 13.The heating device of claim 1, wherein a number of windings on thesecondary induction coil is at least one.
 14. The heating device ofclaim 1, wherein the secondary induction coil has a thickness in a rangefrom 1.0 µm to 1000 µm.
 15. The heating device of claim 1, wherein thesecondary induction coil has a width in a range from 0.1 mm to 5 cm. 16.The heating device of claim 1, wherein windings of the primary inductioncoil are wound onto a ferromagnetic core.
 17. The heating device ofclaim 16, wherein the ferromagnetic core is made of iron or ferrites.18. The heating device of claim 16, wherein the ferromagnetic coreencircles the primary induction coil.
 19. The heating device of claim 1,wherein the controller circuit is further configured to adjust atemperature of the secondary induction coil by adjusting a voltageapplied to the primary induction coil.
 20. The heating device of claim1, wherein the controller circuit is further configured to adjust atemperature of the secondary induction coil by adjusting a frequency ofthe electrical power delivered to the primary induction coil.